Method of making vibratory devices



March 20, 1934. w. s. KELLAR unwnon OF MAKING VIBRATORY nnvxcns Filed Jan. 1:, 19:51

M er/far W 5 A/K/J/ /A? I Patented Mar. 20, 1934 1,91 ,si4 METHOD or MAKING VIBRATORY DEVICES William S. Kellar, Lombard, Ill., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application January is, 1931, Serial No; 508,484

3 Claims. (Cl. 29-4695) This invention relates to vibratory devices and methods ofproducing the same, and more particularly to diaphragms and other vibratory devices formed of aluminum alloys, and to methods of producing such devices.

The object of the invention is to provide an improved and eificient method of producing metallic vibratory devices.

The invention is particularly applicable to the production of diaphragm and other vibratory parts used in the transmission, recording, and reproduction of sound, an example of such parts being a transmitter diaphragm for use in telephonic communication systems. Such diaphragms'must possess the qualities of lightness, strength, and elasticity, and it is an object of the present invention-to produce parts which will meet these as well as other requirements.

In one embodiment, wherein the invention is applied to the production of telephone transmitter diaphragms, the metal from which the diaphragms are to be made consists of'analuminum alloy which is formed into a strip and annealed at a temperature sufficiently' low to avoid discoloring the metal. The annealed strip is then reduced to the thickness desired in the finished diaphragms and the diaphragms are then blanked from the strip. The blanks are then heat-treated at a higher temperature and are shaped, by stamping or otherwise, into their final form immediately after the heat-treatment. The diaphragms are then age hardened for several days The preferred composition of the alloy from which the vibrating parts are made is as follows: 'copperuni 3.15% to 4.50%

and these blanks are then heat-treated by main- 0' taining them at a temperature of from 930 to 960 F. for about seven minutes, coloring, it is desirable to bring all the blanks up to temperature quickly and simultaneously without overheating any of them, hence the blanksshould be scatteredlor arranged in such a way as to expose all their surfaces to the heat of the furnace, rather than to mass or stack them in regular formation, and, only a limited number of blanks should be introduced into the furnace at one time, so that they may be raised to the desired temperature within about two minutes. After being maintained at a temperature of 930 to 960 F. for aboutlseven' minutes, the blanks are formed by stamping into the shape shown in 76 the drawing,,wherein one face of the diaphragm 8 is concave and the other convex, and corrugations 10 extend radially of the diaphragm.

. This forming operation should be performed.

within alimited time, preferably one hour, after 80 the disks are heat-treated, and this may necessitate heat-treating at one time only a limited number of disks corresponding to the number of disks which can bestamped into final form Within one hour. The-necessity for forming the '85 disks quickly after heat-treatment arises from the fact that the alloy age hardens after the heat-treatment and at the end of about one hour has hardened to such an extent that forming it would produce undesirable internal stresses which 00 would tend to produce cracks or flaws in the flnished dia'phragms.

The diaphragms after being formed are age hardened by maintaining them at room temperature for about four days, after which they are ready to be assembled intoa telephone. transmitter such as is shown in the drawing. The material in the finished diaphragm has a tensile strength of about 55,000 pounds per square inch.

To avoid dis- I The invention is also capable ofuse in conto nection with the production of diaphragms or Magnesmm "-"r m 130% membranes designed to respond to pressure fluc- Ma'nganese 40%130 1.90% tuationsin pressure reducing valvesand similar more than apparatus where lightness, strength, and sensi- 50 Alumlmnn. n tivity to variations in pressure are desired. Such of about 660 to 700 F. being preferred. It is diaphragms ormembranes are not usually free to vibrate in the same manner as is the diaphragm above described, but are designed to be moved out of a normal position by exterior forces and to be restored to such normal position by the elasticity of the material, and are therefore intended to be included within the term vibratory devices as it is used in this'application. The term aluminum base alloy is used in the following claims to designate an alloy of the'kind\ described in the above description.

The inventionis also capable of other modifications and embodiments, and its scope is not limited except by the terms of the following claims.

What is claimed is:

- 1. The method of producing'a vibratory device having an irregular cross-section, which comprises reducing to a form having a plane cross- 2. The method of producing a vibratory device "which comprises reducing an aluminum base alloy comprising substantially 4% copper, substantially aluminum, and small amounts of silicon, mangesium, manganese and iron to sheet form, heating the sheet to the vicinity of 660 to 700 F'., cooling the sheet in air, cold working the sheet, heating the sheet to the vicinity of 930 to 960 F. for approximately seven minutes, and forming the sheet into avibratory device within a short time after thelast heat-treatment.

3. The method of producing a vibratory device which comprises reducing an aluminum base alloy to sheet form, heating the sheet to the vicinity of 660 to 700 F., cold working the sheet, heating the sheet to the vicinity of 930 to 960 F. for about seven minutes, and forming the sheet into a vibratory device within a short time after the last heat-treatment.

WILLIAM S. KEILAR. 

